The alpha-isoform of glycogen synthase kinase-3 from rabbit skeletal muscle is inactivated by p70 S6 kinase or MAP kinase-activated protein kinase-1 in vitro

FEBS Lett. 1994 Jan 24;338(1):37-42. doi: 10.1016/0014-5793(94)80112-6.


The alpha-isoform of glycogen synthase kinase-3 (GSK3 alpha) was inactivated by 80% towards a synthetic peptide substrate upon incubation with Mg-ATP and either MAP kinase-activated protein (MAPKAP) kinase-1 or p70 S6 kinase. Inactivation by either kinase resulted from the phosphorylation of Ser-21 and was reversed by treatment with protein phosphatase 2A1. Phosphorylation also decreased GSK3 alpha activity towards glycogen synthase, inhibitor-2 and c-jun. The specificity of GSK3 alpha was similar to GSK3 beta, but with the synthetic peptide substrate heparin stimulated the dephosphorylated form of GSK3 alpha (6-fold) more than GSK3 beta (1.8-fold). After phosphorylation, both isoforms were stimulated 15-20-fold by heparin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors*
  • Glycogen Synthase Kinase 3
  • Glycogen Synthase Kinases
  • In Vitro Techniques
  • Microtubule-Associated Proteins / antagonists & inhibitors*
  • Molecular Sequence Data
  • Muscles / enzymology*
  • Phosphorylation
  • Protein Serine-Threonine Kinases / metabolism*
  • Rabbits
  • Ribosomal Protein S6 Kinases
  • Ribosomal Protein S6 Kinases, 90-kDa


  • Microtubule-Associated Proteins
  • Glycogen Synthase Kinases
  • Protein Serine-Threonine Kinases
  • Ribosomal Protein S6 Kinases
  • Ribosomal Protein S6 Kinases, 90-kDa
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Glycogen Synthase Kinase 3